from tkinter import *
from tkinter.filedialog import askopenfilename
import shelve

root = Tk()
shelvename = askopenfilename().split('.')[0]

root.title(shelvename.split('/')[-1])
db = shelve.open(shelvename)
rec = 0
dbkeys = list(db.keys())
record = db[dbkeys[rec]]
fields = tuple(record.__dict__.keys())
form = Frame(root)
form.pack()
global entries
entries ={}

lab = Label(form, text="key")
ent = Entry(form)
lab.grid(row=0, sticky = E)
ent.grid(row=0, column=1)
entries['key'] = ent


for (ix,label) in enumerate(fields):
    lab = Label(form, text=label)
    ent = Entry(form)
    lab.grid(row=ix+1, sticky = E)
    ent.grid(row=ix+1, column=1)
    entries[label] = ent

def ShowRec(char = ''):
    global rec
    dbkeys = list(db.keys())
    if char =='+':
        if rec<len(dbkeys)-1:
            rec+=1
    elif char == '-':
        if rec>0:
            rec-=1

    record = db[dbkeys[rec]]
    fields = record.__dict__.keys()
    entries['key'].delete(0, END)
    entries['key'].insert(0,str(dbkeys[rec]))
    for label in fields:
        entries[label].delete(0, END)
        entries[label].insert(0,str(getattr(record, label)))

def updateRecord():
    key = entries['key'].get()
    if key in db:
        record = db[key]
    else:
        from person import Person
        record = Person(name='?', job='?')
    for field in fields:
        setattr(record, field, entries[field].get())
    db[key] = record

def deleteRecord():
    global rec
    key = entries['key'].get()
    del db[key]
    rec = 0
    ShowRec()
def clearRec():
    record = db[dbkeys[rec]]
    fields = record.__dict__.keys()
    entries['key'].delete(0, END)
    for label in fields:
        entries[label].delete(0, END)

ShowRec()
root.mainloop()
db.close()

Button(root, text='<<', command = (lambda: ShowRec('-'))).pack(side=LEFT)
Button(root, text='>>', command = (lambda: ShowRec('+'))).pack(side=RIGHT)
Button(root, text='Update', command = (lambda: updateRecord())).pack(side=LEFT)
Button(root, text='Delete', command = (lambda: deleteRecord())).pack(side=RIGHT)
Button(root, text='Clear', command = (lambda: clearRec())).pack(fill=X)